Sewing machine for sewing buttons



Jan. 2, 1968 BQNQ SEWING MACHINE FOR SEWING BUTTONS Filed April 1, 1965 FIG.2

United States Patent 3,361,099 SEWING MACHINE FOR SEWING BUTTONS Luigi Bonn, Pavia, Italy, assignor to Necchi Societa per Azioni, Pavia, Italy Filed Apr. 1, 1965, Ser. No. 444,702 Claims priority, application Italy, Apr. 10, 1964, 7 7 4 3 Claims. (31. 112-459 ABSTRACT OF THE DISCLOSURE The present invention is directed to a sewing machine for sewing buttons with a simple chain-type stitch. Specifically, the invention is directed to providing a mechanism for synchronizing the transverse shiftings of the needle bar with the corresponding transverse shiftings of the auxiliary stitch forming parts.

The auxiliary stitch forming parts comprise, in button sewing machines, a hook and a loop shifter which are keyed on the ends of two parallel shafts which are mount ed in the base portion of the machine housing. In the known procedure for sewing a two or four hole, flat button onto a fabric, the button is secured in place by a special clamp and the needle is alternately introduced through each of a pair of holes so as to effect the sewing stitches beneath said pair of holes.

In order to assure a perfect stitch formation for each hole which the needle passes through, it is essential that the auxiliary stitch forming parts assume the same positions relative to each other, in each of the two alternate sewing positions which corresponds to the separate holes in the button.

An object of the present invention, therefore, is to provide a means whereby the reciprocal movements of the auxiliary stitch forming parts are synchronized or correlated with the transverse reciprocal movements of each other and of the needle bar.

This object generally is realized through the provision of a rotatable disc cam which is driven by the machine main shaft and whose profile is used to regulate the transverse shiftings of the needle bar and also the transverse shiftings of the auxiliary stitch forming parts.

The invention will now be described in greater detail, and other objects thereof will become apparent with reference to the accompanying drawing, wherein:

FIGURE 1 is a vertical sectional view through the machine and shows only those parts which are essential to this invention;

FIGURES 2, 3, and 4 are respective sectional views taken along section lines IIII, III-III, and IV-IV of FIGURE 1.

With reference to FIGURE 1, the machine comprises a housing 10 which includes a lower, horizontal work supporting portion 10a and an upper portion 11 which in turn includes a vertical columnar portion 12 and an upper horizontal portion 13 which terminates in a head 14. The upper portion 13 and the head 14 overhang the work supporting portion 100.

Within the housing 10 there is supported the rotatable "ice main drive shaft 19 which is journalled in bearings 54 and 55 which are secured to said housing. A needle bar support 60 is pivotably mounted to the housing at 63 for reciprocal transverse pivoting about an axis which is parallel to the axis of the main shaft 19. A needle bar 58 is mounted for reciprocatory vertical movement on the needle bar support 60. Rotary movement of shaft 19 is translated into said reciprocatory vertical movement of the bar 58 by means of members 56 and 57 which constitute well known drive connecting means between shaft 19 and said needle bar.

The needle bar support 60 is transversely pivoted about pivot pin 63 by means of reciprocably pivotable shaft 52 which is rigidly secured at one end thereof to pivot arm 59 which in turn is connected to the support 60 through a suitable connecting means. Shaft 52 is pivotably mounted in bearings 51 and 53 which are rigidly mounted on the housing 10.

Vertically aligned beneath the needle 61, which is mounted in the needle bar 58, is a hook 27 and a loop shifter 38 both of which cooperate with the needle to form a stitch. The hook 27 is rigidly keyed on one end of hook shaft 26 which is rotatably driven from the main shaft 19. The rotary driving connection from the main shaft 19 to the hook shaft 26 comprises auxiliary hook shaft 23 rotatably journalled in housing 10 by means of bearings 24 and 28, pulley wheels 20 and 22 respectively rigidly keyed to shafts 19 and 23, belt 21 mounted on said wheels, and an Oldham coupling 25 which drivingly connects shaft 23 to shaft 26 in a manner whereby shaft 23 can continuously rotate shaft 26 while the rotational axis of shaft 26 is reciprocably pivoted about an axis which is parallel to the rotational axis of shaft 26 and to the axis of pin 63. In other words, the rotational axis of shaft 26 is not stationary but, instead, is reciprocably shiftable or oscillatable in correspondence to the transverse shifting of the needle bar 60.

In order to transversely shift the hook shaft 26, this shaft is rotatably mounted in bearings: 29 and 30 which in turn are rigidly mounted on opposite ends of a bridge 31. Bridge 31 comprises rigid pivot pin 34 at one end thereof, this pin being rotatably supported in bearing 36 which is rigid with housing 10. At the other end of bridge 31, the bridge is rotatably journalled on bushing 33 which in turn is rigidly connected to housing 10 by means of rigid support 37. Rotatably mounted within bushing 33 is pin 35 whose ends respectively protrude beyond the ends of bushing 33. Rigidly mounted to the right hand end of pin 35 is the loop shifter 38 which includes an integral lever arm 42 (FIGURE 3).

The left hand end of pin 35 is rigidly connected to follower arm 40 which has a free end which rides against the surface of eccentric 39. Eccentric 39 is rigidly keyed on the hook shaft 26 so as to notate therewith. The free end of follower 40 is resiliently biased against the surface of eccentric 39 by virtue of spring 41 which is connected at one end thereof to housing 10 and at the other end thereof to the free end of arm 42.

In order to synchronize and correlate the transverse reciprocable shiftings of the needle bar support 60 with those of the loop shifter 38 and hook 27, a transverse control cam 15 is provided. This cam is horizontally rotatably mounted in the housing 10 and is rotatably driven by vertical shaft 18 which in turn is drivingly connected to the main shaft 19 in a known manner.

A cam follower device comprises shaft 47 pivotably supported on housing 10 and rigidly connected to a lever arm 46 having a free endwhich includes cam follower roller 17. Roller 17 rides against the profiled surface of cam 15 and an opposite arm of device 47 bears against pin 45. Pin 45 comprises one end of link 44, the opposite end of link 44 comprising pin 43 which is connected to the bridge 31. It is seen, therefore, that rotation of cam 15 causes rocking of shaft 47 in accordance with the roller 17 following the contour of said cam. Rocking of shaft 47 in turn is transmitted to link 44 which linearly reciprocates and thereby pivots bridge 31 about the axis defined by axially aligned pins 34 and 35. This pivoting motion of bridge 31 is in turn simultaneously transmitted to the needle bar support 6% and to the elements 27 and 38 as follows.

The bridge 31 is linked to shaft 52 by means of arm 48 which is integral with bridge 31, and by means of link members 49 and '0. Link melnber 50 is rigid with .shaft 52 while member 49 is pivoted at both its ends to arm 48 and to link 50, respectively. From this it is obvious that pivoting of bridge 31 causes transverse pivoting or rocking of arm 59 and of support 66.

Oscillatory pivoting of bridge 31 also causes a transverse reciprocal shifting of hook shaft 26 and with it, the hook 27. Further, the rotation of eccentric 39 on shaft 26, acts through follower arm 40 to also pivot the pin 35 and with it the loop shifter 38. It is here to he noted that the action of eccentric 39 upon shifter 38 depends upon the combination of two different movements: one being the rotation of eccentric 39 with the hook shaft 26, and the other being the transverse oscillatory position of this same shaft 26. It is for this reason that when the shaft 26 with hook 27 oscillates from the full line sewing position in FIGURE 3 to the dash line sewing position, the shifter 33 does 'not change its position relative to the hook 27 and relative to the axis of the sewing needle 61. In other words, if eccentric 39 were rotatable about a fixed axis instead of being transversely shiftable with shaft 26, the position of the shifter 38 relative to hook 2 7 and to the needle 61 would be different in each of the two transverse sewing positions. But, by transversely shifting the eccentric 39 together with the hook shaft 26, the result is that the relative position of the shifter fork 62 and the hook 27 and needle 61 is maintained constant in all transverse positions of the ook shaft 26.

It is further seen in FIGURE 3 that the trajectory of the biting point of hook 27 and the axis of the needle cross each other in the same horizontal plane in both transverse sewing positions. This is the optimum condi- 4 tion to assure the accomplishment of the most delicate stage in the sewing cycle, that is, the penetration of the hook biting point in the thread loop.

The presently disclosed embodiment is only a preferred embodiment of the invention and is not intended to be limitative of the scope thereof.

What is claimed is:

1. A sewing machine for sewing buttons onto a fabric, comprising: a needle carried by a needle bar, a main drive shaft, means connecting said shaft to said bar to reciprocate said bar, means mounting said bar for transverse movement relative to the axis along which said bar re ciprocates, a hook and a loop shifter for cooperating with said needle to effect stitches, said hook being rotatably mounted about an axis which is transversely shiftable, said loop shifter being pivotably mounted about a fixed axis, a synchronizing means operatively actuated by said main shaft and acting to transversely shift said needle bar and said hook axis synchronously relative to each other.

2. The sewing machine of claim 1, wherein said hook is rigidly mounted on a rotatable hook shaft, means connecting said hook shaft to said main shaft whereby said hook shaft is driven by said main shaft, said hook shaft being transversely shiftable, eccentric means integral with said hook shaft for pivoting said loop shifter.

3. A sewing machine for sewing buttons onto a fabric and comprising a needle bar which is transversely shiftable to either of two sewing positions; a rotary hook and a pivotable loop shifter both aligned with a needle carried by said bar for effecting stitches; said hook being mounted on a hook shaft, said hook shaft being transversely shiftable generally parallelly to the transverse shifting direction of said needle bar, said loop shifter being pivoted about a fixed axis, an eccentric mounted on said hook shaft and associated with said loop shifter to pivotally oscillate said shifter, a rotatable cam operatively connected to said hook shaft and to said needle bar for effecting simultaneous transverse shifting of said hook shaft and said bar.

References Cited UNITED STATES PATENTS 2,495,069 1/1950 McCann 1l2l59X RICHARD J. SCANLAN, JR., Primary Examiner, 

